PMID- 1633843
OWN - NLM
STAT- MEDLINE
DCOM- 19920827
LR  - 20220331
IS  - 0014-5793 (Print)
IS  - 0014-5793 (Linking)
VI  - 302
IP  - 2
DP  - 1992 May 11
TI  - Evidence that dopachrome tautomerase is a ferrous iron-binding glycoprotein.
PG  - 126-8
AB  - Dopachrome tautomerase (DT) (EC 5.3.2.3) is a melanocyte-specific, 
      membrane-associated, heat-labile, non-dialyzable, protease-sensitive factor which 
      catalyzes the isomeric rearrangement of dopachrome to 
      5,6-dihydroxyindole-2-carboxylic acid (DHICA), apparently through a 
      tautomerization reaction. Metal ions such as Cu, Ni, Co, Zn, Mn, Ca, Al, and Fe 
      can also catalyze the dopachrome/DHICA isomerization. How is the reaction 
      regulated in vivo? An attractive possibility would be that DT is a metalloenzyme. 
      Here we present evidence that this may indeed be the case. Purified preparations 
      of DT and tyrosinase, obtained from Cloudman S91 mouse melanoma cells, were 
      assayed in the presence of a variety of metal chelators including EDTA 
      (predominantly Ca and Mg), EGTA (predominantly Ca), phenylthiourea (PTU) 
      (predominantly Cu), 2,2'-dipyridyl (predominantly Fe); 1,10-phenanthroline 
      (predominantly Fe), and 2,3-dihydroxybenzoic acid (predominantly Fe). In 
      addition, DT activity was assayed in the presence of two non-chelating structural 
      analogs of 1,10-phenanthroline. Results were as follows: (i) iron chelators 
      inhibited DT activity with no effects on tyrosinase activity; (ii) inhibition by 
      the chelators was reversible with the addition of ferrous iron; (iii) 
      1,10-phenanthroline pre-complexed to ferrous iron was not inhibitory to DT; (iv) 
      non-chelating analogs of phenanthroline were not inhibitory to DT; (v) PTU was 
      inhibitory to tyrosinase but not DT; (vi) Ca2+ and Mg2+ chelators had little 
      effect on either enzyme activity. Finally, studies with glycosylation inhibitors, 
      glycosylase enzymes, and immobilized lectins, indicated that DT is a 
      glycoprotein. The results suggest that DT is a metal-containing glycosylated 
      enzyme, possibly with ferrous iron at its catalytic center.
FAU - Chakraborty, A K
AU  - Chakraborty AK
AD  - Department of Dermatology, Yale University School of Medicine, New Haven, CT 
      06510.
FAU - Orlow, S J
AU  - Orlow SJ
FAU - Pawelek, J M
AU  - Pawelek JM
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, Non-P.H.S.
PL  - England
TA  - FEBS Lett
JT  - FEBS letters
JID - 0155157
RN  - 0 (Chelating Agents)
RN  - 0 (Ferrous Compounds)
RN  - 0 (Glycoproteins)
RN  - 0 (Hydroxybenzoates)
RN  - 0 (Indolequinones)
RN  - 0 (Indoles)
RN  - 0 (Phenanthrolines)
RN  - 0 (Quinones)
RN  - 3571-34-4 (dopachrome)
RN  - 551W113ZEP (2,2'-Dipyridyl)
RN  - 70D5FBB392 (2,3-dihydroxybenzoic acid)
RN  - 9G34HU7RV0 (Edetic Acid)
RN  - EC 1.14.18.1 (Monophenol Monooxygenase)
RN  - EC 5.- (Isomerases)
RN  - EC 5.3.- (Intramolecular Oxidoreductases)
RN  - EC 5.3.3.12 (dopachrome isomerase)
RN  - W4X6ZO7939 (1,10-phenanthroline)
SB  - IM
MH  - 2,2'-Dipyridyl/pharmacology
MH  - Animals
MH  - Chelating Agents/pharmacology
MH  - Edetic Acid/pharmacology
MH  - Ferrous Compounds/*metabolism/pharmacology
MH  - Glycoproteins/*metabolism
MH  - Hydroxybenzoates/pharmacology
MH  - *Indolequinones
MH  - Indoles/metabolism
MH  - *Intramolecular Oxidoreductases
MH  - Isomerases/antagonists & inhibitors/*metabolism
MH  - Melanoma, Experimental/enzymology
MH  - Mice
MH  - Monophenol Monooxygenase/antagonists & inhibitors/metabolism
MH  - Phenanthrolines/pharmacology
MH  - Quinones/metabolism
MH  - Tumor Cells, Cultured
EDAT- 1992/05/11 00:00
MHDA- 1992/05/11 00:01
CRDT- 1992/05/11 00:00
PHST- 1992/05/11 00:00 [pubmed]
PHST- 1992/05/11 00:01 [medline]
PHST- 1992/05/11 00:00 [entrez]
AID - 0014-5793(92)80421-C [pii]
AID - 10.1016/0014-5793(92)80421-c [doi]
PST - ppublish
SO  - FEBS Lett. 1992 May 11;302(2):126-8. doi: 10.1016/0014-5793(92)80421-c.